CHANTHABURI, Thailand — When a plain white van pulled into the driveway of a humble home in the eastern Thai province of Chanthaburi around midday recently, five elderly townspeople climbed in and settled themselves among pillows and blankets for a two-hour ride to the Cambodian border.

On arrival at the immigration checkpoint, a representative of a casino just across the frontier in Pailin, Cambodia, handed 500 baht ($15) vouchers to each Thai passenger. The voucher would cover their first bet at the baccarat tables and if successful, generate just enough winnings to cover the roundtrip charge for the shuttle.